a. Field of the Invention
The instant invention relates to catheters that are used in the human body. In particular, the instant invention relates to a catheter with embedded internal components. The present invention also relates to methods of manufacturing a catheter with embedded internal components.
b. Background Art
Catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, the catheter is manipulated through the patient's vasculature and to the intended site, for example a site within the patient's heart.
A typical electrophysiology catheter includes an elongate shaft. The shaft includes one or more lumens therethrough. The catheter's internal components will generally be disposed within the lumens and/or routed to the proximal end of the catheter through the lumens. For example, a pull wire to deflect the distal end of the catheter may extend from the distal end of the catheter to the proximal end of the catheter through a pull wire lumen.
An electrophysiology catheter will also generally include one or more electrodes on the distal end of the shaft. The electrodes may be used for ablation, diagnosis, or the like. Each electrode is coupled to a lead wire. The lead wires are generally strung through holes that are pierced in the wall of the catheter shaft. The electrode may then be swaged onto the shaft, covering the hole through which the lead wire extends, and adhesive applied around the edge of the electrode. Typically, all lead wires extend to the proximal end of the shaft through a single, central lumen. Exemplary electrophysiology catheters are disclosed in U.S. Pat. Nos. 5,395,328 and 5,395,329, which are hereby incorporated by reference as though fully set forth herein.
In the typical construction of an electrophysiology catheter described above, it is possible for blood or other fluids to bypass the adhesive seal around the electrode. If this happens, the fluid has a direct path into the catheter through the lead wire hole. This is commonly referred to as “fluid ingress,” and is known to cause electrical noise on ECGs and shorts between electrodes.
In the case of deflectable (steerable) catheters, the internal components are forced to move when the catheter is deflected. Over several deflections, lead wires may become tangled, break, or lose their insulative coating as they rub against each other and the wall of the catheter shaft. This, in turn, may lead to reduced efficacy of the electrophysiology catheter.
Furthermore, the lumen must be large enough to house all internal components, such as pull wires, lead wires, signal wires, and the like. However, the outer diameter of the catheter shaft must remain small enough for the catheter to fit within the relatively narrow passages of the patient's vasculature. It is thus necessary to reduce the wall thickness of the catheter shaft, which reduces the stiffness of the shaft, potentially leading to undesirable flexure of the distal end during insertion into the patient's vasculature.